Keyboard assembly

ABSTRACT

A keyboard assembly having a plurality of reed switches mounted on a base member, a plurality of key assemblies mounted on a mounting plate and a plurality of movable switch actuators mounted adjacent the switches. Each switch actuator comprises a bail pivotally mounted above the base member, a magnet carried by the bail and a spring for biasing the magnet-bail assembly away from the associated switch. Each key assembly comprises a reciprocable slide, a key top, a bias spring and a stop member for limiting the amount of travel of the slide in the return direction. A resilient cushioning material is provided on the underside of each bail and a contact portion of each slide to substantially reduce mechanical noise and wear.

United States Patent Adahan [54] KEYBOARD ASSEMBLY [72] Inventor: Carmeli Adahan, Berkeley, Calif.

[73] Assignee: The Singer Company, New York,

[22] Filed: Aug. 27, 1971 [21] Appl. No.: 175,527

[52] U.S. Cl ..335/206 [51] Int. Cl. ..Hlh 3/12, HOlh 41/08 [58] Field of Search ..335/206,'205, 207; 340/347 [56] References Cited UNITED STATES PATENTS 3,430,226 2/1969 Chow et al ..340/347 DA 3,486,145 12/1969 Paige ..335/206 3,539,958 11/1970 Van Gelder et al. ..335/206 3,292,125 12/1966 Berry ..335/206 Primary Examiner-R. N. Envall, Jr. Attorney-Warren P. Kujawa et al.

[57] ABSTRACT A keyboard assembly having a plurality of reed switches mounted on a base member, a plurality of key assemblies mounted on a mounting plate and a plurality of movable switch actuators mounted adjacent the switches. Each switch actuator comprises a bail pivotally mounted above the base member, a magnet carried by the bail and a spring for biasing the magnet-bail assembly away from the associated switch. Each key assembly comprises a reciprocable slide, a key top, a bias spring and a stop member for limiting the amount of travel of the slide in the return direction. A resilient cushioning material is provided on the underside of each bail and a contact portion of each slide to substantially reduce mechanical noise and wear.

8 Claims, 7 Drawing Figures 15 j ow te 50 QQ i L Ln 2 50 so 16 so 49 45 #8 4 11 Z6 45 16 T "l l6 2s rLL G9 V Y i i N i; x i

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SHEU 1 OF 2 i N N O J3 1 m T N E V m BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to keyboard assemblies of the type used in the data processing art, in electronic desk top calculators, and the like. More particularly, this invention relates to keyboard assemblies employing one I or more switches to provide signals indicating the actuation of a key.

2. Brief Description of the Prior Art Many types of keyboard assemblies have been proposed for use as the operator input unit for different types of utilization devices, e.g., electronic desk top calculators, video display systems, computers and the like. All such prior art keyboard assemblies are provided with individual key mechanisms and associated switching circuits for providing unique electrical signals which specify each actuated key. Depending on the application of a given device, these signals may correspond to numeric data, an alphanumeric character, or a machine function. Further, all prior art keyboards are provided with various combinations of the numeric data keys, alphanumeric character keys and machine function keys: some having keys of only one type; others having different types of keys.

In order to unambiguously specify an actuated key, prior art keyboards employ one of several known coding systems. One such coding system employs a separate switch for each key. When a given key is actuated in a keyboard employing such a system, the associated switch is actuated, thereby providing a unique electrical signal identifying. the actuated key to the utilization device. While such a coding system is effective, the cost increases disproportionately as the number of keys increases. For keyboards requiring a large number of keys, this coding system can be economically unfeasible.

Other coding systems employ different known types of binary codes for identifying an actuated key. These systems utilize several common switches for all keys, the number of switches depending on the type of binary code employed. A four-bit code, e.g., commonly requires four switches to identify each actuated key; a five-bit code requires five switches; etc.

Known keyboards are typically designed with a special purpose in mind. As a result, while the design of a particular keyboard may be well suited for the particular intended use, efforts to utilize that keyboard with a different type of utilization device are usually quite unsuccessful. This limited adaptability significantly reduces the usefulnessof such a keyboard. While attempts have been made to provide a keyboard assembly which is adaptable to a wide variety of uses, such devices generally have met with little success.

SUMMARY OF THE INVENTION The present invention is directed to a keyboard which is compatible with a wide variety of utilization devices, and is inexpensive to manufacture, simple to install and highly reliable in performance. The preferred embodiment of the invention comprises a plurality of magnetic reed switches mounted on a base member, a plurality of key assemblies mounted on a mounting plate, and a plurality of movable switch actuators mounted adjacent the switches. Each switch actuator comprises a bail member pivotally mounted above the base member, a magnet carried by the bail and a spring for biasing the magnet-bail assembly away from the associated switch. Each key assembly comprises a reciprocable slide having a number of extended fingers for controlling the pivotal movement of different bails, a key top, a return bias spring for maintaining the key in a nonactuated position, and a stop member for limiting the amount of travel of the slide in the return direction. By preselecting the number and arrangement of fingers on each slide, any one of a number of coding systems can be providedv A resilient cushioning material is provided on a portion on the underside of each bail and of each extended slide finger to substantially reduce mechanical noise and wear.

For a further understanding of the nature and advantages of the invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view of a preferred embodiment of the invention taken along lines l1 of FIG. 2;

FIG. 2 is a front elevation of a preferred embodiment of the invention; and

FIGS. 3-7 are enlarged detail views illustrating the cooperation between various elements of the preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings, FIGS. 1 and 2 illustrate a preferred embodiment of the invention. A housing 10 comprises side walls 11, 12, top mounting plate 13 and base member 14. Although side walls ll, 12 may comprise separate elements attached to mounting plate 13 in any one of several known ways, in the preferred embodiment side walls 11, 12 are formed integrally with mounting plate 13 from any one of several known moldable materials. Side wall 12 is provided with a notch 15 for snugly receiving one end of base member 14. Base member 14 is retained by notch 15 and by a single screw 16 threaded into side wall 11. As will be evident to those skilled in the art, other mounting arrangements can be employed for base member 14.

A plurality of magnetic reed switches 16 are disposed along the upper surface of base member 14 at spaced intervals. As will be apparent to those skilled in the art, each reed switch comprises a pair of reed contacts enclosed in a hermetically sealed envelope, usually glass. The contacts are so constructed and arranged within the envelope that the positioning of a magnet in proximity to the switch results in the actuation of that switch, usually by causing a pair of normally opened contacts to close; while removing the magnet from the vicinity of the switch causes the contacts to revert to their normally opened state. The contacts of each switch are electrically coupled to the utilization device by electrically conductive paths (not shown) within or on the surface of base member 14. These paths preferably lead to and terminate at extended end portion 18 of base member 14, which can be sized to receive a standard electrical plug.

Disposed transversely of housing above base member 14 are a number of generally U-shaped bail members formed from any suitable material, e.g., a nonmagnetic alloy wire. Each bail member 20 is pivotally supported by side walls 11, 12 and restrained against excessive lateral motion by end portions 21, 22. Each bail member 20 is biased to an upright position by a tension spring 24 attached at one end to a post 23 extending from side wall 11 and at the other end to end portion 21 of bail member 20. To prevent spring 24 from disengaging from bail member 20, end portion 21 is provided with a circumferential slot 25 for accommodating the lower looped end 26 of spring 24, as shown in FIGS. 3 and 4. Alternatively, end portion 21 may be formed with a spring retaining bend 27 as shown in FIG. 5. Other equivalent configurations will occur to those skilled in the art.

As best shown in FIGS. 6 and 7, attached to each bail member 20 by a suitable fastener, such as clip 28 (FIG. 6) or clip 28' (FIG. 7), is a permanent magnet 30. Each magnet 30 is positioned on bail member 20 adjacent a corresponding reed switch 16. As most clearly shown in FIG. 1, the angle of repose of bail member 20 when in the upright rest position is chosen in a manner described below to hold magnet 30 a sufficient distance away from associated switch 16 to prevent actuation of switch 16 by magnet 30. When bail member 20 is pivotally moved in the manner described below, magnet 30 is brought into close proximity with switch 16 so that switch 16 is actuated.

As seen most clearly in FIG. 4, a comer portion of each bail member 20 is provided with a spot of resilient material 32, e.g., RTV silicone rubber, to provide a mechanical cushion between the bail member 20 and the upper surface of base member 14. The mechanical cushion provided by material 32 prevents contact between the lower surface of bail member 20 and the upper surface of base member 14, which eliminates mechanical wear and significantly reduces operating noise.

Reciprocably disposed in housing 10 are a number of key assemblies 35. As shown most clearly in FIG. 1, each key. assembly 35 includes a slide provided with a plurality of downwardly extending fingers 42 each having a spot of resilient material 43 on the underside thereof for contacting the surface of an associated bail member 20. A key top 45 is attached to a neck portion 46 of slide 40 by any suitable means, e.g., press fitting. A return bias spring 48 is disposed between the top of mounting plate 13 and key top 45. Each slide is further provided with a downwardly extending guide portion 49 which is slidably received by an associated guide aperture in base member 14.

As shown most clearly in FIG. 2, each key assembly 35 is provided with a peg 50 anchored in an aperture in neck portion 46 for limiting the travel of the key assembly in the return direction. I In operation, each key assembly is normally held in the nonactuated or rest position by bias spring 48 and stop peg 50, while each bail member 20 is held in the rest position by bias spring 24. In this rest position, the surface of each bail member 20 rests against resilient material 43 adhered on the underside of the individual slide fingers 42. The keyboard elements are dimensioned so that each magnet 30 is maintained a sufficient distance removed from the associated reed switch 16 to allow the contacts therein to achieve their nonactuated configuration. When a key is depressed by the operator, as shown in broken lines for the forward most key assembly in the cluster of key assemblies to the right in FIG. 1, and in solid lines for the same key assembly in FIG. 2, the bail members 20 located below the corresponding slide fingers 42 are pivoted clockwise, moving the associated magnets 30 into close proximity with their corresponding reed switches 16 and actuating these reed switches. When the key is released by the operator, the key assembly is raised by bias spring 48, while the lower bail members 20 are raised by their associated bias springs 24 until stop peg 50 terminates movement in the return direction. During motion of slide 40 in the downward and return directions, guide portion 49 reciprocates in its corresponding guide aperture in base member 14 to restrict the motion of all fingers 42 to a plurality of substantially vertical paths.

It is important to note that motion is transmitted to each bail member 20 from its corresponding slide finger 42 through resilient material 43. This material eliminates mechanical wear on the bail 20 surface and the bottom face of finger 42 which would ordinarily occur in the absence of material 43. It is also noted that the entire slide finger 42 may be constructed from any one of several known plastic materials, e.g., Delrin or Teflon, of sufficient strength to operate its associated bail, yet sufficiently resilient to eliminate mechanical wear. Material 43 along with resilient material 32 adhered to the underside of each bail member 20 also provides a resilient stop touch when a key assembly has been fully actuated by the operator. This resilient stop touch has been found to substantially reduce operator fatigue experienced with prior art keyboards not having this feature. Moreover, resilient materials 32, 43 eliminate contact between solid elements of the keyboard, e.g., the underside of bail member 20 and the upper surface of base member 14. This reduces the operating noise level of the keyboard, which is found to be highly distracting to the operator using known keyboards not equipped with such a silencing feature.

Keyboards constructed according to the invention can be simply adapted to many different types of coding systems by preselecting the number of slide fingers 42 on each slide 40 and the number of bails 20 and switches 16. As shown in FIG. 1, e.g., a four-bit binary code may be employed by providing four switches 16, corresponding bails 20, and three slide fingers 42 per slide 40. If the switches 16 are arbitrarily designated from right to left as switch Nos. 1, 2, 3, and 4, it is seen that the rightmost key assembly 35 is uniquely identified by the binary number 1 l 10, where the binary 1 corresponds to an actuated switch, the binary 0 corresponds to a nonactuated switch, and the four binary digits represent the states of the switches l4 in ascending order of significance. Similarly, the center key assembly 35 is uniquely identified by the binary numbers 01 l 1, while the leftmost key assembly 35 is uniquely identified by the binary number 1011. As will be evident to those skilled in the art, other four-bit binary codes may be employed for these keys; also, binary codes other than the four-bit code illustrated may be provided by preselecting different slide finger 42 and switch 16 configurations. Similarly, each slide 40 may be provided with a single slide finger 42 for actuating a single reed switch 16 if such a coding system is desired.

To facilitate the preselection of a code system, each slide 40 may be provided with a standard number of slide fingers 42, each of which may be readily removed during assembly of the keyboard. This may be done by providing a groove along the junction between each slide finger 42 and its corresponding slide 40, so that undesired fingers 42 may be removed by breaking the finger along this groove. Other such constructions will occur to those skilled in the art.

Keyboards constructed according to the invention readily lend themselves to a wide variety of key configurations. In the preferred embodiment illustrated in FIGS. 1 and 2, e.g., two clusters of key assemblies are shown, the cluster on the left comprising a horizontal row of three keys and the cluster on the right comprising a vertical row of three keys as viewed from the top of the keyboard. Each cluster may be formed using three types of standard key tops 45 andstandard slides 40. As is evident in FIG. 2, the three different types of standard key tops 45 differ only by the location of the press fit aperture for receiving the neck portion 46 of each slide 40: in type 1 this aperture is formed left of center; in type 2 the same aperture is formed right of center, in type 3 this aperture is formed substantially at the center. The effect of combining all three types to form a horizontal row of keys is visible in the left cluster; while the effect of combining all three types to form a vertical row of keys is visible in the right cluster.

As will be evident to those skilled in the art, other key clusters and different key placements may be readily achieved with the standard key tops shown in accordance with the requirements of the particular utilization device with which the keyboard is to be associated and in accordance with the operator key configuration preferences. Standardization may be easily achieved by providing mounting plate 13 and base member 14 with a number of aperture defining knockout sections which can be easily removed during assembly of a keyboard. In this way, each keyboard can be easily tailored to a given use.

While the foregoing provides a full disclosure of the preferred embodiment of the invention, it is understood that various modifications, alternate constructions and equivalents may be employed without departing from the true spirit and scope of the invention. For example, other types of switches than reed switches 16 capable of being actuated by a proximity switch actuator device may be employed in keyboards constructed according to the invention. Therefore, the above description and illustrations should not be construed as limiting the scope of the invention, which is solely defined by the appended claims.

What is claimed is:

l. A keyboard assembly comprising:

a base member;

a magnetic reed switch mounted on said base member;

a generally U-shaped bail member pivotally mounted about the ends thereof adjacent said switch;

a magnet carried by said bail member for actuating said switch when moved into close proximity 6 thereto; meansfor biasing said magnet in a direction away from said i wit h; and a key assem ly or operating said ball member, said key assembly including a reciprocable slide member having a resilient contact portion for contacting said bail member, a key top mounted on the keyboard end of said slide member, slide member biasing means for normally biasing said slide member to a nonactuated position, and a stop member for limiting the travel of said slide member in the nonactuated direction.

2. The apparatus of claim 1 wherein said bail is positioned above said base member and is provided with a resilient cushioning material on a portion of the underside thereof for substantially reducing mechanical noise and wear when said bail contacts said base member.

3. The apparatus of claim 1 wherein said base member is provided with a guide hole and said slide member includes a guide portion slidably engageable with said guide hole.

4. The apparatus of claim 1 wherein said contact portion comprises a resilient cushioning material engageable with a surface portion of said bail member for reducing mechanical wear.

5. A keyboard assembly comprising:

a base member;

a plurality of magnetic reed switches mounted on said base member;

a plurality of generally U-shaped bail members each pivotally mounted about the ends thereof adjacent different individual ones of said plurality of switches;

a magnet carried by each said bail member for actuating an associated one of said switches when moved into close proximity thereto;

means for biasing each said magnet in a direction away from the switch associated thereto; and

a plurality of key assemblies for controlling the position of selected ones of said plurality of bail members, each key assembly including a reciprocable slide having at least one resilient contact portion engageable with one of said bail members, a key top mounted on the keyboard end of said slide, means for biasing said slide to a nonactuated position, and a stop member for limiting the travel of each said slide in the nonactuated direction.

6. The apparatus of claim 5 wherein each of said bail members is positioned above said base member and provided with a resilient cushioning material on a portion of the underside thereof for substantially reducing mechanical noise and wear when said bail contacts said base member.

7. The apparatus of claim 5 wherein said base member is provided with a plurality of guide holes and each one of said slides has a guide portion slidably engageable with a different one of said guide holes.

8. The apparatus of claim 5 wherein each of said contact portions comprises a resilient cushioning material engageable with a surface portion of said bail member for reducing mechanical wear. 

1. A keyboard assembly comprising: a base member; a magnetic reed switch mounted on said base member; a generally U-shaped bail member pivotally mounted about the ends thereof adjacent said switch; a magnet carried by said bail member for actuating said switch when moved into close proximity thereto; means for biasing said magnet in a direction away from said switch; and a key assembly for operating said bail member, said key assembly including a reciprocable slide member having a resilient contact portion for contacting said bail member, a key top mounted on the keyboard end of said slide member, slide member biasing means for normally biasing said slide member to a nonactuated position, and a stop member for limiting the travel of said slide member in the nonactuated direction.
 2. The apparatus of claim 1 wherein said bail is positioned above said base member and is provided with a resilient cushioning material on a portion of the underside thereof for substantially reducing mechanical noise and wear when said bail contacts said base member.
 3. The apparatus of claim 1 wherein said base member is provided with a guide hole and said slide member includes a guide portion slidably engageable with said guide hole.
 4. The apparatus of claim 1 wherein said contact portion comprises a resilient cushioning material engageable with a surface portion of said bail member for reducing mechanical wear.
 5. A keyboard assembly comprising: a base member; a plurality of magnetic reed switches mounted on said base member; a plurality of generally U-shaped bail members each pivotally mounted about the ends thereof adjacent different individual ones of said plurality of switches; a magnet carried by each said bail member for actuating an associated one of said switches when moved into close proximity thereto; means for biasing each said magnet in a direction away from the switch associated thereto; and a plurality of key assemblies for controlling the position of selected ones of said plurality of bail members, each key assembly including a reciprocable slide having at least one resilient contact portion engageable with one of said bail members, a key top mounted on the keyboard end of said slide, means for biasing said slide to a nonactuated position, and a stop member for limiting the travel of each said slide in the nonactuated direction.
 6. The apparatus of claim 5 wherein each of said bail members is positioned above said base member and provided with a resilient cushioning material on a portion of the underside thereof for substantially reduciNg mechanical noise and wear when said bail contacts said base member.
 7. The apparatus of claim 5 wherein said base member is provided with a plurality of guide holes and each one of said slides has a guide portion slidably engageable with a different one of said guide holes.
 8. The apparatus of claim 5 wherein each of said contact portions comprises a resilient cushioning material engageable with a surface portion of said bail member for reducing mechanical wear. 